Traits drive global wood decomposition rates more than climate

Abstract

Wood decomposition is a major component of the global carbon cycle. Decomposition rates vary across climate gradients, which is thought to reflect the effects of temperature and moisture on the metabolic kinetics of decomposers. However, decomposition rates also vary with wood traits, which may reflect the influence of stoichiometry on decomposer metabolism as well as geometry relating the surface areas that decomposers colonize with the volumes they consume. In this paper, we combined metabolic and geometric scaling theories to formalize hypotheses regarding the drivers of wood decomposition rates, and assessed these hypotheses using a global compilation of data on climate, wood traits, and wood decomposition rates. Our results are consistent with predictions from both metabolic and geometric scaling theories. Approximately half of the global variation in decomposition rates was explained by wood traits (nitrogen content and diameter), whereas only a fifth was explained by climate variables (air temperature, precipitation, and relative humidity). These results indicate that global variation in wood decomposition rates is best explained by stoichiometric and geometric wood traits. Our findings suggest that inclusion of wood traits in global carbon cycle models can improve predictions of carbon fluxes from wood decomposition.

Accurate forest projections require long‐term wood decay experiments because plant trait effects change through time

“…Furthermore, the temperature gradients present at our site (<1°C) are much smaller than gradients observed in studies that examine broad biogeographic gradients in wood decay (Adair et al, ; Bradford et al, ). Nevertheless, variation in initial wood traits more strongly influenced wood decay than environmental variability, which is consistent with global patterns (Hu et al, ; Weedon et al, ).…”

“…Nevertheless, variation in initial wood traits more strongly influenced wood decay than environmental variability, which is consistent with global patterns (Hu et al, 2018;Weedon et al, 2009).…”

“…Wood density is a key plant functional trait with an ambiguous effect on decay (Pietsch et al, ). A recent global meta‐analysis found that denser wood decayed more quickly (Hu et al, ) in contrast to specific experiments that have either demonstrated slower decay for denser wood (Hérault et al, ) or no wood density effect (Freschet, Weedon, Aerts, van Hal, & Cornelissen, ; Kahl et al, ; Weedon et al, ). Our results can resolve these discrepancies by demonstrating that wood density may not control decay rates per se, but rather how decay rates change through time (i.e.…”

Plant phylogenetic history explains in‐stream decomposition at a global scale

“…Leaf litter decomposability is influenced by a plant's position on the leaf economics spectrum (Díaz et al, ; Wright et al, ). In terrestrial systems, plant traits have been found to explain the decomposition rate of leaves (Cornwell et al, ) and wood (Hu et al, ) more than climatic factors. We were unable to include specific leaf traits as explanatory variables in our study due to inconsistent reporting of leaf traits in the published studies.…”

Wood decomposition is more rapid on than off termite mounds in an African savanna

“…It is surprising that the relationship between denser wood and slower decomposition does not hold when macrodetritivores are excluded. Other traits, such as wood nutrient concentrations, can also influence decomposition rates (Hu et al 2018). Studies in the wet tropics have shown considerable variation in wood nutrient concentrations among and within species and have indicated that these species and site-determined variables can dominate variation in decomposition rates (e.g., Heineman et al 2016).…”